As shown in FIG. 7, a tandem press line which comprises plural press machines disposed in parallel is configured to have a work transfer device A disposed between mutually adjacent press machine P1 and press machine P2, to discharge the work from the press processing position of the previous step by the work transfer device A and to feed the work into the press processing position of the next step.
The above-described work transfer device A is provided with a beam B which is extended in the horizontal direction along the work transfer direction and installed between the mutually adjacent press machine P1 and press machine P2, and a carrier (supporting portion) C which is moved in the longitudinal direction (work transfer direction) of the beam B by drive means (not shown).
Additionally, the work transfer device A is provided with a transfer arm E with a work holding means D such as a vacuum cup device disposed at the bottom end, and the transfer arm E is supported to be oscillatable to the carrier C and movable along its axial direction by drive means (not shown).
The above-mentioned work transfer device A is configured such that the carrier C is moved along the beam B, the transfer arm E is oscillated with respect to the carrier C and moved in its axial direction, and the work holding means D is moved horizontally as indicated by arrow L to transfer the work between the press machine P1 and the press machine P2.
Here, a power line and a signal line for driving the transfer arm E and cables such as hydraulic piping, air piping and the like for operating the work holding means D which is disposed at the bottom end of the transfer arm E are extended from the top end of the transfer arm E in the work transfer device A, and these cables are connected to a power source, an air compressor and the like which are separately disposed on the press machines P1, P2.
Meanwhile, the above-mentioned transfer arm E exhibits complex behavior to horizontally move the work holding means D as described above, and the top end of the transfer arm E requires a particularly large range of motion. Therefore, it is necessary to treat the cable so as not to be swung around by the movement of the transfer arm E.
As a device capable of appropriately treating the cable, a cable holding device which is provided with a mechanism which can hold the middle part of the cable and can follow the movement of the movable body is provided.
A conventional cable holding device H shown in FIG. 8 and FIG. 9 has a lower rack arm I which is pin-connected to a top end Et of a transfer arm E and an upper rack arm J which is pin-connected to a cable fixing portion F located above the transfer arm E, and is configured with a pair of mutually parallel middle rack arms Ka, Kb pin-connected to free ends of the lower rack arm I and the upper rack arm J.
Since the cable holding device H configured as described above is deformed as the transfer arm E moves as shown in FIG. 8 and FIG. 9, a cable G which is connected to the cable fixing portion F located above the top end Et of the transfer arm E is held by the cable holding device H. Then, the cable G is not swung around unnecessarily by the behavior of the transfer arm E and can be prevented from being damaged unexpectedly.
Patent Literature 1: Japanese Utility Model Application Laid-open No. 1-118832